Railway traffic controlling apparatus



June 6, 1939.

F. H. NICHOLSON RAILWAY TRAFFIC CONTROLLING APPARATUS Filed Sept. 28,1937 4 Sheets-Sheet l INVENTOR HIS ATTORNEY RAILWAY TRAFFIC CONTROLLINGAPPARATUS 4 Sheets-Sheet 2 Filed Sept. 28, 1937 5 JeCondQe lease 4Second a v q INVENTOR I: S m g Frank H 17015012.

a s 03 BY N w w A Q\ H13 ATTORNEY June 6, 1939. F. H. NICHOLSON2,160,894

RAILWAY TRAFFIC CONTROLLING APPARATUS 4 Sheets-Sheet 3 Filed Sept. 28,1937 mm bar F r WN VRw mm 63 .mmiwmq E35 E h EXE EBMGNN E mi 2 J1me1939- PH. NICHOLSON RAILWAY TRAFFIC CONTROLLING APPARATUS Filed Sept.28, 1937 4 Sheets-Sheet 4 @MQQQ W J H .@sob

23$ mm E l 5 EH f @MSU @QEG M H F l l l IN NTOR Hank cbolkson.

HAS ATTORNEY Patented June 6 1939 PATENT OFFICE RAILWAY TRAFFICCONTROLLING APPARATUS Frank H. Nicholson, Wilkinsburg, Pa., assignor toThe Union Switch & Signal Company, Swissvale, Pa., a corporation ofPennsylvania.

Application September 28, 1937, Serial No. 166,101

16 Claims.

My invention relates to railway traffic controlling apparatus, andparticularly to apparatus of the code signal type.

A feature of my invention is the provision of novel and improvedapparatus for signal systems for railway trains to indicate by means ofsignal indications in the locomotive cab the approach to fixed trackhazards, and the degree or nature of such hazards, as well as toindicate in the cab the different traffic conditions in advance ofthe'trains -A further feature of my invention is the provision ofapparatus of the type contemplated wherewith the signal indications forthe fixed hazards are obtained without changing the essential characterof the codes used to reflect trafiic conditions in the frequency codesystems now in use on railroads. In other words, a feature of myinvention is the provision of apparatus for a group code system forindicating different degrees offixed track hazards and apparatus forpafrequency code system for indicating different traffic conditions withthe two apparatuses so interrelated that each functions withoutinterference to the other. A still further featureof the invention isthe provision of apparatus ofthe group code type with a retardationsufficient to compel two counts of the code before the correspondingsignal indication is displayed; Again, a feature of the invention is theprovision of apparatus of the group code type wherewith the retardationof the apparatus is automatically adjusted to fit the incoming code.Another feature of the invention is the provision of apparatus of thetype here involved whereby the signal indications for the fixed trackhazards are suppressed when low speed traffic conditions exist. Otherfeatures and advantages of my invention will appear as the specificationprogresses.

I shall describe. one form of apparatus embodying my invention, andshall then point out the novel features thereof in claims.

In the accompanying drawings, Figs. 1 and 2 are diagrammatic views of apreferred form of apparatus embodying my invention, Fig. 1 being'thetrackway'portion of the apparatus and Fig. 2 being the train-carriedportion. Fig. 3A is a diagrammatic view of one form of code transmitterthat may be used to provide the frequency codes for the apparatus ofFig. 1. Figs. 33, 3C and 3D are diagrammatic views of the codetransmitter of Fig. 3A when modified so as to arrange the impulses ofthe different frequency codes into different groups; Figs. 4A, 4B and 4Care diagrams illustrating the various combinations of frequency codesand group codes provided by the code transmitters of Figs. 3A, 3B, 3Cand 3D.

In each of the views, similar reference char acters designate similarparts.

Referring to Fig. 1, a stretch of railway track 5 over which trafficnormally moves in the direction indicated by an arrow is formed by theusual insulated rail joints into successive track sections, only theadjacent ends of the two track sections IT and 2T being shown for the 1sake of simplicity. The junction of sections IT and 2T constitutes asignal location identified by the reference character Al. It will'beunderstood that the entire stretch of railway is formed into successivetrack sections, the junctions of adjacent sections constituting signallocations similar to the location Al.

This stretch of railway is characterized by curves, cuts, fills,tunnels, bridges and other fixed track hazards which require differentper- 2 missible maximum speeds at different locations. As shown at theright-hand end of Fig. l, the track section 2T includes a fixed trackhazard at which a predetermined permissible maximum speed under alltrafiic conditions is required for safety;

The track sections of this-stretch of railway are each provided withtrackway apparatus as required for a combined wayside and cab signalsystem of the frequency code type, the apparatus at each signal locationbeing substantially the same except as modified at locations in thevicinity of fixed track hazards to superpose on the frequency codes agroup code to indicate the approach to the fixed track hazard and thedegree of such fixed hazard.

The trackway apparatus of each track section includes a track circuitconsisting of a source of alternating current connected across the railsat the exit end of the section and a track relay connected across therails at the entrance of the section. Hence, the source ofcurrent forthe track circuit of section IT and the track relay for the trackcircuit of section 2T are located at the signal location Al. Theimmediate source of current for the track circuit of section IT is thesecondary winding 10 of a track transformer Tl, the primary winding 1|of which is supplied with coded alternating current in a manner to belater described. The alternating current may be of any desired frequencysuch as, for example, 100 cycles per second; The alternating currentwouldpreferably be supplied to signal location Al and to the othersignal locations by means of a transmission line and the usual linetransformer, both of which are not shown in the drawings for the sake ofsimplicity, the two terminals of the source of alternating current beingindicated by the reference characters BX and OK.

The track relay TR for the track circuit of section 2T is a codefollowing direct cmrent relay. The operating winding of relay TB issupplied with rectified current through the usual transformer-rectifierR2, the input terminals of which are connected across the track rails ofsection 2T over wires 12 and I3, and the output terminals of which areconnected with the operating winding of relay TR over wires 14 and 1E.The transformer-rectifier R2 may be any one of several types well-knownin the art, and is shown conventionally since its structure forms nopart of my present invention. It follows that as long as the trackcircuit of section 2T is supplied with alternating current the trackrelay TB is energized and picked up, causing its contact members 9 and10 toengage front contacts ii and i2, respectively, but that when noalternating current or an insufficient amount flows in the track circuitadjacent the entrance of section 2T the relay TR is deenergized andreleased, causing its contact members 9 and it! to engage back contactsl3 and I 4, respectively. Furthermore, when the alternating currentsupplied to the track circuit of section 2T is periodically interruptedor coded at a code frequency of, say 180, 120 or 75 times per minute,the relay TR is picked up during the on period of each code cycle and isreleased during the off period of each cod-e cycle. In accordance withusual practice, the code frequency of the track circuit current is 180per minute when clear traffic conditions exist, is 120 per minute under"approach-restricting traffic conditions, and is 75 per minute underapproach trafiic conditions. If the track section 2T is occupied, thecoded track circuit current is shunted by the train ahead and does notreach the track relay TR. or the following train, giving thecaution-slow speed traffic condition.

The trackway apparatus at location A! includes a code transmitter CT andfive control relays ASA, BSA, H, JA and JB for controlling the supply ofcurrent to the track circuit for the section IT in the rear of section2T, as well as for controlling the operating circuits of a waysidesignal SI.

The code transmitter CT may be any one of several types and is hereshown as being of the motor type, the operating or motor winding 39 ofwhich is constantly supplied with alternating current so that the codetransmitter is continuously active. When, in the vicinity of a signallocation, no fixed track hazard exists that requires for safety apermissible maximum speed less than the prescribed permissible mazn'mumspeed for all trains of the railway, the code transmitter is constructedto provide the difierent frequency codes in accordance with thedifferent trafiicconditions as set forth hereinbefore. Under thesecircumstances, the construction of the code transmitter would preferablybe as disclosed in Fig. 3A. When a fixed track hazard exists in thevicinity of a signal location, the construction of the code transmitteris modified so as to arrange the frequency code impulses into differentsuccessive groups, the modification of the transmitter being selectedaccording to the degree or nature of the fixed hazard. To aid in theunderstanding of my invention, I shall assume that three different groupcodes are provided, a first one of which would be used when the fixedtrack hazard is of the first degree and a permissible maximum speed of,say, miles per hour under all trafiic conditions is prescribed. A secondgroup code would be used when the nature of the fixed hazard is of thesecond degree and the prescribed maximum speed is, say, 50 miles perhour; and the third group code would be selected when the nature of thefixed hazard is of the third degree that requires for safety apermissible maximum speed of, say, 25 miles per hour. For readyreference, I shall hereinafter refer to these different group codes asfirst degree or 80, second degree or 50, and third degree or 25. Thepreferred modifications for the code transmitter so as to provide the80, 50 and 25 group codes are disclosed in Figs. 33, 3C and 3D,respectively. It will be understood, of course, that my invention is notlimited to the three codes for fixed hazards or to the maximum speedlimits stated above, and these three codes will serve to illustrate theinvention.

Looking at Fig. 3A, the motor element 39 of the code transmitter drivesa shaft indicated by a dotted line 15 at the rate of, say, 15revolutions per minute. Three code cams I6, I? and iii are mounted infixed relation with the shaft [5 and rotate in the clockwise directionas viewed in Fig. 3A at 15 revolutions per minute, the cams beingpreferably of suitable insulating material. Cams I6, I1 and I8 areconstructed with 5, 8 and 12 teeth, respectively. A code contact memberP5 is associated with cam l 6, the arrangement being such that thecontact member 15 is actuated by each tooth of cam l6 to close a contactl5al5b and to open the contact between successive teeth. Hence, thecontact 15al 5b is opened and closed 75 (15x5) times per minute. A codecontact member I20 is associated with cam I1 and is actuated to close acontact l2ila-I2llb by each tooth of the cam, with the result that thecontact lZiiw-lZfib is closed and opened at the rate of (15x8) times perminute. In a similar manner, a code contact member I80 is associatedwith cam l8 and is operated by each tooth of the cam to close a contactl80al80b, with the result that contact l80a.l8llb is opened and closed(15x12) times per minute. It follows that the current flowing in acircuit in which the contact IBUa-IBOb is interposed is periodicallyinterrupted or coded 180 times per minute, or three times per second.Such coding of current is illustrated by the I80 code curve (uppercurve) of Fig. 4A, the raised portions representing the on periodsduring which current flows and the depressed portions of the curveillustrating the off periods during which no current flows. In thiscase, each period of a code cycle is equal to one-sixth of a second. TheI20 code curve of Fig. 4B represents in a similar manner the currentflowing in a circuit in which the code contact |29a.l2ilb is interposed,each on and off period of a code cycle being substantially equal toone-fourth of a second. Likewise, the 75 code curve of Fig. 4Crepresents the current flow in a circuit in which the contact "ma-15b isinterposed, the on and off periods of each code cycle being equal tosubstantially four-tenths of a second.

When a fixed track hazard of the first degree exists in the vicinity ofa signal location, the code transmitter of Fig. 3A is modified so thatthe frequency code impulses are grouped into successive groups of fiveimpulses each, and each group is separated from the preceding andsucceeding groups by a predetermined interval. In theform of theinvention here disclosed,.an off intervalor pause equivalent to threenormal off intervals is inserted after fivencycles of normal code.Looking at Fig. 3B, the shaft I5 of the code transmitter drives throughsuitable gear trains three shafts indicated by the dotted lines I5a, I5band I50, the gear trains being so proportioned that shaft [511 rotatesat 12.5 revolutions per minute, shaft I5b rotates at revolutions perminute and shaft I50 rotates at 30 revolutions per minute. Three codeselectors or cams 40, II and 42 of suitable insulating rnaterial arefixed on the shafts I5a, I 5b and I50, respectively. Each of the codeselectors 40, 4I

and 42 is formed with six teeth and is mutilated hazard of the firstdegree.

by the removal of one tooth. The code contact members I5, I20 and I80are actuated by the cams 40, 4| and 42, respectively. It is clear thatwith the code transmitter constructed as indicated in Fig. 3B thecurrent flowing in a circuit in which the contact I80a--I80b isinterposed will be frequency and group coded in the manner illustratedby the'curve I80-80 code of Fig. 4A to represent clear trafiicconditions and a fixed hazard of the first degree, the cause or offinterval between successive code groups being substantially equal toone-half second. The current flowing in a circuit in which the contact.

I20a-I20b is interposed will be frequency and group coded in the mannerillustrated by the curve I20-80 code of Fig. 413 to representapproach-restricting trafiic conditions and a fixed The current flowingin a circuit in which the contact 'I5a-I5b is interposed will befrequency and group coded in the manner illustrated by the curve 15-80code of Fig. 40 to represent approach traffic conditions and a fixedhazard of the first degree.

When the fixed hazard is of the second degree and a permissible maximumspeed of 50 miles per hour is prescribed, the code transmitter ismodified so that the frequency code impulses are grouped into successivegroups of four impulses each and an off interval equivalent to threenormal off intervals is inserted between the successive code groups. Inthis case, the code transmitter may be constructed in the manner shownin Fig. 30. Looking at Fig. 3C, two shafts indicated by the dotted linesI5d and I5e are driven from shaft I5 through suitable gear trains sothat the shaft I5d rotates at 24 revolutions per minute and. the shaftI5e rotates at 36 revolutions per minute, it being recalled that shaftI5 rotates at 15 revolutions per minute. Three code selectors or cams43, 44 and 45 of suitable insulating material are fixed on the shaft I5,I512 and I5e, respectively. Each of the cams 43, 44 and 45 is formed.with five teeth, and is mutilated by the removal of one tooth. The codecontact members 15, I20 and I80 are actuated by the three cams 43, 44and 45, respectively, as in previous cases. With the code transmitterconstructed in this manner, the current in the circuit in which therespective code contacts are interposed will be coded in the mannerillustrated by the curves I8050' code of Fig. 4A, I20--50 code of Fig.4B and-'I5-50 code of Fig. 40.

When the fixed track hazard is of the third degree and the permissiblemaximum speed of miles per hour is prescribed, the code transmitter ismodified. so that the frequency code impulses are grouped intosuccessive groups of three impulses-each, and an off interval equivalent'to three normal off intervals is inserted between the successive codegroups. To obtain such a code arrangement, the code transmitter may beconstructed as disclosed in Fig. 3D. In this case, the shaft I5 drivesthrough gear trains three shafts indicated by three dotted lines I5 I5'gand I5h, the gear trains being of such-ratio that the shafts I51, I59and I5h rotate at 18.75, and 45 revolutions per minute, respectively.Three code selectors or cams 45, 41 and 48 of suitable insulatingmaterial are fixed on the shafts I51, I5g and I5h, respectively, andeach is formed' with four teeth and is mutilated by the removal of onetooth. The code contact members fected when the code transmitter is ofthe construction of Figs. 3A. 3B, 3C and 3D.

Referring to Fig. 1 and assuming that the control relays occupy theposition illustrated in the drawings, which, as will shortly appear. isthe position of the relays under clear traffic conditions for section2T, a circuit can be traced from the BX terminal of the source ofalternating current over code contact I80a-I80b of the code transmitterCT, front contacts 24, 2I, 22 and 23 of relays JA, H. BSA and ASA,respectively, primary winding 'II- of transformer Ti, and to the CXterminal of the current source. Again, when the relay JB is picked upand relay JA is released, as will be the condition of the relays whenapproach restricting traffic conditions exist for section 2T, the abovetraced circuit is completed at the front contact I9 of relay JB and theback contact 20 of relay JA. Consequently, when the control relays ofsignal location AI are energized in accordance with either clear orapproach-restrictingtraffic conditions for section 2T, the track circuitcurrent for the section IT is coded according to the I80 frequency code.In the event no fixed track hazard exists in the vicinity of section 2T,then this frequency code alone would be impressed upon the track circuitcurrent for section IT. If the fixed hazard shown at the right-hand endof section 2T is one of the first degree and the code transmitter ofFig. 1 is modified according to the construction disclosed by Fig. 3B,then the current supplied to the track circuit of section IT over thecircuit traced above would be frequency and group coded as illustratedby the I8080 code curve of Fig. 4A. If the track hazard of section 2T isone of V the second degree and the code transmitter is modifiedaccording to the construction of Fig. 3C, the above traced circuit,including code contact I 80a--I80b would supply to the track circuit ofsection IT current, frequency and group coded as illustrated by theI80'--50 code curve of Fig. 4A. Again, if the fixed hazard in thevicinity of section 2T is one of the third degree and the codetransmitter is modified according to the construction of Fig. 3D,current coded according to the I80-25 code curve of Fig. 4A is suppliedto the track circuit of section IT by the circuit including the codecontact IBM-I801).

Assuming the relays JA and JB are both released and the relays ASA, BSAand H are picked up, which, as will shortly appear, is the condition 0fthe relays under approach trafiic conditions for section 2T, a circuitextends from BX terminal of the source of alternating current over codecontact l2fial2!3b, back contacts 28 and 20 of relays JB and JA,respectively, front contacts ill, 22 and 23 of relays H, BSA and ASA,respectively, primary winding TI and terminal CX. With the codetransmitter CT modified to agree with the nature of the fixed trackhazard in the vicinity of section 2T, the track circuit current forsection iT would be frequency and group coded by this circuit includingcode contact HEEL-12 b according to the l20-80 code, I20 53 code ori23-25 code, of Fig. 413 depending upon the nature of the fixed trackhazard.

Assuming that track section 2T is occupied and the track relay TRinactive and all the control relays released, a circuit extends from theBX terminal over back contacts 26 and 21 of relays BSA and ASA,respectively, code contact 15a15b, primary winding '5! of transformer TIand CK terminal, and the track circuit current for section lT is codedat the (5 frequency code to refleet approach traffic conditions forsection IT. Modification of the code transmitter to agree with thenature of the fixed hazard of Fig. 1 results in the current supplied tothe track circuit of section IT over this circuit, including codecontact l5ai5b, being coded according to the Htcode, 'l55i3 code or15-25 code of Fig. 40, depending upon the nature of the track hazard.

On the assumption no fixed track hazard exists along the track sectionnext in advance of section 2T, that is, the section next to the right asviewed in Fig. 1, the track circuit for the section 2T will be coded atthe frequency code according to trafiic conditions in the manner justexplained in connection with the track circuit for section 5T. If cleartrafiic conditions exist and the track circuit current of section ET isof the I80 frequency code, the track relay TR is operated in step withthis code frequency to alternately close the contacts 9-H and -l3, aswell as to alternately close the contacts I 0! 2 and Hil4. With thecontacts 9-H and 9-43 alternately closed, current is alternatelysupplied to the two portions of the winding 226 of an autotransformer T2from a source of direct current, the two terminals of which areidentified by the reference characters B and C. It follows that anelectromotive force is induced in the winding 226 of a frequencycorresponding to the I80 code frequency. The winding 226 of transformerT2 is connected with the operating winding of relay JA through a filterrectifier 228 which is proportioned and adjusted to pass and rectifycurrent of a frequency corresponding to the i80 code and to suppressother frequencies. Hence, relay JA is energized and picked up inresponse to the I86 code frequency for the track circuit current ofsection 2T.

With approach restricting traffic conditions in advance of section 2Tand the track circuit current for the section 2T coded at the I28frequency code, relay TR is operated in step with this frequency, andthe resultant electromo-tive force induced in the winding 226 is of thefrequency corresponding to the I20 code. The Winding 2% is connectedwith the operating winding of relay JB through a filter rectifier 221which is proportioned and adjusted to pass and rectify current of thefrequency corresponding to the H25) code and to suppress otherfrequencies, and hence relay JB is energized and picked up in responseto the I20 code for the track circuit of section 2T.

If approach traffic conditions exist for section 2T and its trackcircuit current is coded at the 15 frequency code, the resultantelectromotive force induced in the winding 226 of transformer T2 will beof a frequency outside of the pass band of the filter rectifiers 221 and228, and both relays JA and JB will be deenergized.

Starting from the time no current is supplied 7 to the relay TR and itscontact members 9 and Hi are stationary in engagement with theirrespective back contacts and all the control relays are released, andassuming that current of the l 80 code frequency is supplied to thetrack circuit for section 2T, the relay TR is energized to lift itscontact members 9 and II] into engagement with the front contacts H andi2, respectively, during the on period of the first impulse. The closingof contact Ill-l2 completes a simple circuit easily traced for relayASA, and that relay is picked up. Relay ASA is provided with slowrelease characteristics by virtue of a snubbing resistor 29 and remainspicked up from one code impulse to the next. On the off period of thefirst impulse the relay TR is released closing contact lil|4, andcurrent fiows from the B terminal over contact li3l4, front contact 38of relay ASA, winding of relay BSA and to the C terminal, and relay BSAis picked up. Relay BSA is provided with slow release characteristics byvirtue of resistor 3! connected across the winding of relay BSA overfront contact 30 of relay ASA. At the on period of the second impulse,relay TR is picked up closing contact lii-l2 again, and current issupplied from the B terminal over contact llll2, resistor 32, backcontact 33 of relay H, back contact 34 of relay JA, front contact 35 ofrelay BSA, winding of relay H and to the C terminal, and relay H ispicked up, the back contact 33 being of such construction that relay Hpicks up over its own back contact. Relay H is provided with slowrelease characteristics by virtue of resistor 38. Relay H is providedwith a stick circuit which includes its own front contact 38, backcontact 34 of relay JA, and front contact 35 of relay BSA, and is alsoprovided with an energizing circuit including front contact 3'! of relayJA and front contact 35 of relay BSA.

From this point on, the relays ASA, BSA and H are retained picked up aslong as the code frequency persists. After a few code impulses, theelectromotive force induced in the Winding 225 of transformer T2 becomeseffective to select relay JA, and that relay is picked up.

In the event current of the l2!) code is supplied to the track circuitfor section 2T immediately subsequent to a period when no current issupplied and the control relays are all released, the operation of therelays ASA, BSA and H in response .31

t0 the first two impulses of the code is the same as described inconnection with the H30 code. This time, relay JB is selected and ispicked up. In the event current of the 15 code is supplied to the trackcircuit for section 2T subsequent to a t" period when no current issupplied, the operation of the relays ASA, BSA and H is again the same,but this time the relays JA and JB remain deenergized. It is to be notedthat relays ASA,

BSA and H are sequentially picked up in response to the first and secondimpulses of each code frequency of the track circuit current of sectoin2T, are retained picked up by continued operation of track relay TR, arereleased when relay TR is not operated, and these relays control overill front and back contacts .the supply of track circuit current forsection IT. The relays ASA, BSA and H provide broken down insulated railjoint protection desirable in signal systems of the type here involvedbut which protection need not here be described in detail since it formsno part of my present invention and is not required for a fullunderstanding of the invention.

It is to be pointed out that in the event the track circuit current forsection 2T is group coded according to some fixed track hazard as wellas being frequency coded according to different traffic conditions, theoperation of the control relays of Fig. 1 is substantially the same asdescribed hereinbefore and the relays are retained energized since theresistors 29, 3| and 3B are proportioned to provide the respective relaywith a slow release period sufficient to bridge the off period insertedbetween code groups. Also, the circuits for the relays JA and JB areproportioned and adjusted so that when one of these relays is selectedin response to a frequency code it re mains picked up during the offperiod inserted between the code groups.

Location Al is provided with a wayside signal SI for governing trafiicthrough the section 2T.

The signal SI may be any one of the standard types and is here shownas-a position light signal capable of displaying clear,approach-restricting, approach and stop indications. The operatingcircuits for the signal SI are shown at the lower portoin of Fig. 1 andare governed by the control relays according to standard practice, andit is thought to be unnecessary to describe these circuits in detail.

Referring to Fig. 2, the train-carried portion of the apparatus includesas essential elements pick-up apparatus, code responsive apparatus forgoverning a traffic cab indicator and other code responsive apparatusfor governing a fixed hazard cab indicator.

The pick-up apparatus includes two magnetizable cores 49 and 49a locatedin advance of the first pair of locomotive wheels and disposed ininductive relation with the two track rails according to usual practice.The core 49 is provided with a winding 5|, and the core 49a is providedwith a winding 52, the two windings being connected so thatelectromotive forces induced therein by alternating current flowing inthe two rails in opposite directions are additive. The two windings 5|and 52 are connected with the input terminals of an amplifier AM, theoutput terminals of amplifier AM being in turn connected with theoperating winding of a code following master relay MR. The amplifier AMis shown conventionally only for the sake of simplicity, since it may beany one of several well-known types. The master relay MR is preferablyof the direct current polar type commonly employed in frequency codesignal systems for railroads. As is usual practice, the relay MR iscontrolled by the amplifier AM in a manner so that the building up'ofenergy induced in the I windings 5| and .52'causesan impulse of currentin the operating winding .of relay MR which is of a polarity that willposition the armature .53 of relay .MR in the right-hand position, thatis, in the position illustrated by the dotted line in Fig. 2. The dyingawayofenergy induced in the windings 5| and 52 causes a current impulsein the winding of relay MR which is of a polarity that positions thearmature 53 .in the left-hand position, that is, in the positionillustrated by thesoli-d line in Fig. .2. .It follows that thearmature..53 is operated in step with the code .impulses in alternatingcurrent flowing in the track circuit, includingLthe track rails. Thatis, when the track circuit .ofa section is supplied with frequency codesand group codesexplained hereinbefore in connection with the trackwayapparatus of Fig. 1, the armature 53 is operated at the correspondingfrequency code and is .held stationary at the left-hand position duringthe interval inserted between the code groups. The master relay MRgoverns the apparatus responsive to the frequency codes and alsooperates a code following repeater relay MRI, which relay MRI in turngoverns the apparatus responsive to the group codes.

The apparatus responsive to the frequency codes includes adecoding unitDC I, three control relays A, R and L, and a cab ind cator TS. Currentimpulses are supplied to the input terminals of the decoding unit DCIover the armature 53 of relay MR, and the output terminals of the unitare connected to the operating windings of the relays A, R and L, aswill be readily understood by an inspection of Fig. 2.

The decoding unit DCI may be any one of several types well known to theart, and is shown conventionally only in order to simplify the drawingsas much as possible. sufficient for the present application to point outthat the decoding unit DClis selectively responsive to the differentfrequency codes so that relay L is energized and picked up on each ofthe 180, 120 and '75 frequency codes, relay R is energized and picked upon the 120 frequency code only, and relay A is energized and picked upon the 1-80 frequency code only. The relays L, R and A areeach providedwith slow release characteristics so that the relay, when picked up, itretained picked up during the interval inserted between the various codegroups referred to hereinbefore.

The relays L, R and A govern the circuits for the cab indicator TS forindicating in the locomotive cab the traffic condition corresponding tothe frequency code picked up from the track rails. With relay A pickedup in response to the 180 code, closing its front contacts 54 and 55, acircuit is completed for the indicator lamp 56, and the lamp 56 isilluminated to display a clear cab signal. When relay R is picked up inresponse to the 120 code .and relay A is deenergized, a circuit iscompleted, including back contact 51 of relay A and front contact 58 ofrelay R on one side, and including back contact 59 of relay A and frontcontact 60 of relay R on the other side, for the two lamps 61a and fill)in parallel, and these two lamps are illuminated to display theapproach-restricting cab signal. When relays A and R are both releasedand relay L is picked up in response to the '75 code, a circuit iscompleted from the B terminal over back contacts 51 and 62 of relays Aand R, respectively, front contact 53 of relay L, lamp 64, front contact65 of relay L, back contacts 66 and 59 of relays R and A, respectively,and terminal 0, and lamp 64 is illuminated to display the approach cabsignal. When there is an absence of code current in the track rails andrelay MR is not operated and all the relays A, R and L are released, thelamp-61 of indicator TS is provided with .a circuit including a backcontact It is deemed of each of the three control relays in series, aswill be readily understood by an inspection of Fig. 2, and lamp 6'! isilluminated to display a ,When relays A and R are deenergized and relayL is energized in response to the '75 frequency code, positive andnegative energy are impressed upon the terminals PL and NL,respectively. When relays A, R and L are all released in response tocaution-slow speed traffic conditions, positive and negative energy areimpressed on the terminals PS and NS, respectively.

With the master relay MR operating in. the manner explained above,positive energy is alternately impressed on the terminals PI and P3,which terminals are connected with the outside terminals of theoperating winding of the repeater relay MRI. The mid terminal of thewinding of relay MRI is connected with the common or C terminal of thecurrent source. When positive energy is impressed on terminal P3, therelay MRI is energized with a polarity such that its code contactmembers 68 and 69 are moved to the lower position, as viewed in Fig. 2.When positive energy is impressed on terminal Pl, the relay MRI isenergized with a polarity such that its contact members 68 and 69 aremoved to the raised position, as viewed in Fig. 2. It follows that thecode following repeater relay MRI is operated to repeat the codeoperating the master relay MR, and the code contact members 68 and 69are retained in their lower positions during an interval insertedbetween the code groups. The relay MRI governs the apparatus responsiveto the code groups in accordance with the code group impressed on thetrack circuit current by the track- Way apparatus to reflect a fixedtrack hazard in the vicinity of the track section.

The essential elements of the apparatus responsive to the group codesconsist of a decoding unit designated as a whole by the referencecharacter DCE, a retardation governing device including relays LC andAP, three control relays CI C2 and C3, a cab indicator HS, anacknowledging device including a manually operated switch SW, relay SPCand a Whistle magnet WM, and a signal suppressing relay LP.

The decoding unit DC2 consists of a relay X and a chain of six countingrelays l to 6, inclusive. The relays 4, and 6 of the counting chain ofrelays govern the control relays CI, C2 and C3, respectively, as willlater appear. The control relays CI, C2 and C3 are provided with slowrelease characteristics of the order indicated on the drawing to requireat least two operations of the relays of the counting chain of relays toeffect a change in the position of the control relays. The controlrelays CI, C2 and C3 in turn govern the circuits for the lamps of theindicator HS in a manner to later appear. The relay LP is provided toprevent the display of the hazard indicator I-IS during a caution-slowspeed traffic condition.

The relay LC of the retardation device causes the decoding unit DC2 toremain inoperative when the current picked up from the track circuit isfrequency coded only, the relay AP automatically adjusting theretardation action of relay LC to fit the normal off period of thefrequency code received. The relay LC causes operation of the decodingunit D02 according to the group code when the track circuit current isboth frequency and group coded.

It is believed that the operation of the apparatus governed by therepeater relay MRI in response to the different group codes for thedifferent fixed track hazards can best be understood by a description ofits operation.

In Fig. 2, the relays responsive to the group codes are all illustratedin the released position ready to respond to any incoming code pickedfrom the track rails. I shall first describe in step-by-step fashion theoperations following the picking up of a I80 frequency code current. Theon period of the first impulse picked up causes relay MRI to lift itscontact members 68 and 69 into engagement with contacts TI and I8,respectively. A circuit is completed from' the B terminal of the currentsource over contact 68TI, back contact 19 of relay X, back contacts 280,BI, 82, 83, 8d and 85 of relays I, 2, 3, I, 5 and 6, respectively,winding of relay LC and to the C terminal, and relay LC is picked up.With relay LC picked up, another circuit is completed from B terminalover front contact 86 of relay LC, contact Ell-78 of relay MRI, backcontact Bl of relay I, winding of relay X, front contact 88 of relay LCand to the C terminal, and relay X is also picked up duringthe on periodof the first impulse. When relay MRI operates its contacts 68 and i323to the lower position during the off period of the first impulse, relayLC remains picked up due to the slow release period established byvirtue of a resistor I 89 and a rectifier 99 connected across itsoperating win-ding. During the off period of the first impulse, relay Xis retained energized over a stick circuit including two branch paths,one path of which extends from B. terminal over contact 68-9I, frontcontact 92 of relay X, winding of relay X, front contact 88 of relay LCand C terminal. The other branch path extends from B terminal over frontcontact 89 of relay X, back contact 87 of relay I, Winding of relay Xand front contact 83 to the C terminal. With relay X thus retainedenergized during the off period of the first impulse, a circuit can betraced from the B terminal over front contact 86 of relay LC, contact59-93 of relay lVLRI, front contact 941 of relay X, back contacts 95, 96and 9! of relays 6, 4 and 2, respectively, winding of relay I and to theC terminal, and relay I is picked up. Relay I is then retained energizedover a stick circuit including B terminal, front contact 86 of relay LC,front contact 98 and winding of relay I, and to the C terminal. Itfollows that relay I of the counting chain of relays is picked up andretained energized in response to the first impulse.

When relay MRI lifts its contact members 68 and 69 in response to the onperiod of the second impulse, the relay LC is provided with anenergizing impulse over' a circuit including contact fill- 11 and thefront contact 99 of relay LC. Both paths of the stick circuit for therelay X are now opened and relay X is released during the on period ofthe second impulse. The off period of the second impulse causes relayMRI to lower its contact members 68 and 59. Since relay X is nowreleased, the closing of contact 6993 completes a circuit from Bterminal over front contact 88, contact 29-93, back contact III!) ofrelay X, back contacts I III and H12 of relays 5 and 3, respectively,front contact H13 of relay I, winding of relay 2 and to the C terminal,and relay 2 is picked up. Relay 2 is then retained energized over astick circuit including its own front contact I134 and .the frontcontact 286 of' relay LC. Thus, relay 2 of the counting chain of relaysis picked upand retained energizedin response to the second impulse.

With relay MR'I lifting its contact members 68 and 69 during the onperiod of the third impulse, relay .LC is again provided with anenergizing impulse, and a circuit is formed for relay X from B terminalover front contact 86, contact 53-73, back contact H35 of relay 3, frontcontact I56 of relay 2, winding of .relay X and to the C terminal, andrelay X is again picked up. Relay X is now provided with a stick circuitincluding two branch paths, one of which involves contact -68-9I ofrelay MRI and front contact '92 of relay X, and the other path of whichinvolves B terminal, front contact85, back contact I of relay 3, frontcontact Hit of relay 2, winding of relay X, front contact 38 of relayLCand terminal C.

With contact members 68 and 69 operated to the lower position inresponse to the off period of the third impulse, a circuit is formed forrelay S'Wliich extends from B terminal over front contact 86, contact39- 93, front contact '94 of relay X, back contacts 95 and 96 of relays6 and 4, real spectively, front contact I!" of relay 2, winding of relay3 and C terminal, and relay 3 is picked up. Relay 3 is then retainedenergized over a stick circuit including its own front contact I08 andfront contact 86 of relay LC. Hence, during the third impulse the relay3 of the counting chain of relays is picked up and retained energized.

The on period of the fourth impulse causes relay MRl to lift contactmembers 68 and 69, and relay LC is again provided with an energizingimpulse. Relay X is now deenergized and releases during the on period ofthe fourth impulse, since both paths of its stick circuit are open. Theoff period of the fourth impulse shifts contact members 68 and 59 backto the lower position and completes a circuit from B terminalover frontcontact 86, contact 69-93, back contact Hit of relay X, back contact IGIof relay 5, front contact I 59 of relay 3, winding of relay d and Cterminal, and relay 4 is picked up. Relay 4 is then held energized overa stick circuit including its own front contact Ill] and front contact86 of relay LC. Consequently, relay t of the counting chain of relays isoperated during the fourth impulse.

The on period of the fifth impulse causes contact members '38 and 69 tobe shifted back to the raised position and a circuit is formed for relayX at contact 69-18, back contact Iii of relay 5 and front contact II2 ofrelay 4. Relay X is again provided with a stick circuit including twobranch paths, one of which includes its own front contact 92 and contact-68--9I, and the other of which includes its own front contact 89, backcontact III of relay 5 and front contact H2 of relay 4. Contact members'68 and 59 are next shifted back to the lower position during the offperiod of the fifth impulse. Since relay X is retained energized, acircuit is formed from B terminal over front contact 86, contact frontcontact 94 of relay X, back contact 95 of relay 5, front contact H3 ofrelay winding of relay 5 and to the C terminal, and relay 5 is picked upand retained energized over a stick circuit including its own frontcontact Ht and front contact 86 of relay LC. Thus, relay 5 is picked upin response to the fifth impulse.

The on period of the sixth impulse shifts contact members :58 and 69 tothe raised position; and ,relay Xis'released since both paths of itsstick circuit are now open. When contact members 68 and 69 are shiftedto the lower position during theoif period of the sixth impulse, acircuit is formed from B terminal over front contact :85, .contactGil-93, back contact Hill of relay front contact H5 of relay 5, windingof relay 15 and to the .C terminal, and relay 5 is picked up andretained energized over a stick circuit including its own front contactH5 and front contact .85 of relay LC. It follows that relay 6 is pickedup by the sixth impulse.

'Ihe fon period of the seventh impulse shifts the contact members 58 andI39 to the raised position to again provide relay LC with an energizingimpulse and to complete a circuit for relay X at contact'69l'8 and frontcontact II! of relayfi, and relay X is then. retained energized over astick circuit including its own front contact 89, front contact II? ofrelay ii, and front contact 88+of relay 'LC. Each subsequent impulsecauses contact members 68 and 69 to be lifted and relay LC provided withan energizing impulse, with the result that relay LC, relay X and eachrelay of the chain of counting relays are retained energized, therelaysof the chain of relays being retained energized over stick cir--cuits each of which includes front contact 85 of relay LC and relay Xbeing energized over a stickcircuit including front contact ll? of relay5 and front contact-88 of relay LC.

When counting relay 4 is picked up, a circuit is formed forthecontrolrelay C E, and that relay is energized. This circuit can be traced fromterminal B over front contact II8 of relay LC, front contact H9 of relay4, winding of relay Cl, front'contact IZl of relay 4, front contact Bilof relay -LC and-to theC' terminal. The picking up of-counting relay "5,closing its front contacts I22 and I23, completes a similar circuit forrelay C2, and relay C2 is energized. Likewise, the picking :up ofcounting relay 6, closing its front .contacts 1-24 and I25, completes acircuit easily traced for relay C3, and that relay is energized. Itfollows that all three of the control relays Cl, C2 -and-C3 areenergized in response to the 180 frequency code.

Since relay LC is picked up during the on period of the first impulseand is subsequently retained energized in response to reception of the180' frequency code current, the relay LP is energized during each offperiod of the code impulses. The circuit for relay LP includes terminalB, front contact BIS of relay LC, contact 69- 93, winding of relay LP,frontcontact 88 of relay LC and to the C terminal; Relay LP is slowreleasing in character, and hence remains picked up from one codeimpulse to the next. When relay LP is picked up, closing its frontcontacts I26 and "I21, a circuit easily traced is completed for "thehazard lamp I-IAZ of indicator HS, and that lamp is illuminated. Whenthe control relays C I, O2 and C3 are all energized, a circuit is formedfor the NO lamp of indicator HS. This circuit for the NO lamp involvesthe elements, B terminal, front contact I25 of relay LP, front contactsE28, I29 and I35 of relays 'CI, 02 and C3, respectively, the NO lamp,front contacts I3I, I32 and I33 of relays C3, C2 and CI, respectively,and front contact I 21 of relay LP to the C terminal. It follows thatthe no hazard indication is displayed by the indicator HS when currentcoded at the 189 frequency code is picked up from the track circuit.

Assuming next that current of the 120 frequency code is picked up fromthe track rails and relays MR and MRI are operated at the frequency rateof 120 times per minute, the operation of relay LC and the relays of thedecoding unit DCZ in response to the first six impulses of the codecurrent is substantially the same as explained in connection with thefirst six code impulses of the I86 code current, the retardation periodin the release of relay LC as provided by resistor 589 and rectifier 90being alittle greater than one-fourth second and thus sufficient tobridge the normal off periods of the code current. Hence, the no hazardcab signal is displayed by indicator HS when the track circuit currentis of the 120 frequency code.

In the event current of the 75 frequency code is picked up from thetrack rails and relays MR. and MRE are operated at the rate of 75 timesper minute, the operation of the relay LC and the relays of the decodingunit D02 is substantially the same as explained hereinbefore, since theretardation period in the release of relay LC is increased so that it issufficient to bridge the normal off periods of the 75 frequency codecurrent. It will be recalled that, when relays R and A are released andrelay L is picked up in response to 75 frequency code current, energy isimpressed upon the terminals PL and NL, and hence relay AP is energizedand picked up, closing its front contact I34 in response to current ofthe 75 frequency code. The closing of front contact connects a resistorI35 in parallel with resistor 589 across the winding of relay LC toincrease its slow release period to a little over four-tenths of asecond.

With the apparatus actuated to display the no hazard cab signal inresponse to either the 180, 120 or '75 code current, a circuit is formedfor the whistle magnet WM and the whistle I36 is retained silent. Thiscircuit can be traced from terminal B over front contact I26 of relayLP, front contacts I28, I29 and I30 of relays CI, C2 and C3,respectively, wire I37, back contact I38 of relay SPC, normally closedcontact I39 of switch SW, front contact MI) of relay LP, operatingwinding of whistle magnet WM, front contact Mi of relay LP, back contactI42 of relay SPC, wire hi3, front contacts I3I, I32, I33 and i2! and tothe C terminal.

I shall next take up the operating steps which follow when thelocomotive enters a track section in the vicinity of a fixed trackhazard and a group code is superposed on the traific frequency code. Ishall assume that the track hazard is one of the first degree and thatthe code picked up from the track rails is of the 80 code, andconsequently each group of five code impulses is separated from thepreceding and succeeding groups by an interval equivalent to threenormal off periods of the code current. I shall also assume that theapparatus associated with the indicator HS has previously been operatedin a manner set forth hereinbefore so as to cause the no hazard cabsignal to be displayed. It is to be recalled that resistor 689 andrectifier 9Q establish a release period for relay LC which is slightlygreater than one-fourth of a second in order to span the normal offperiod of the 120 code impulses and that the release period of the relayLC is increased to something over fourtenths second to span the normaloff period of the 75 code frequency impulses. Hence, under the l8080code the release period of relay LC is of the order of one-fourth of a.second and at the first interval or pause, which is of the order ofone-half second, interposed between two code groups the relay LC isreleased. When relay LC is released, opening its front contact 86interposed in the stick circuits for the counting relays, the countingrelays are all deenergized and immediately released, relay X also beingreleased since its stick circuit is opened at both front contact ill ofrelay 6 and front contact 88 of relay LC. Reenergization of relay LC inresponse to the first impulse of the next code group causes the countingrelays to be sequentially operated in the manner already explained. Atthe next long 01f period or pause the relay LC is again released and thecounting relays deenergized and then again operated during the next codegroup. Since there are but five impulses in each group, the relay 6never picked up, with the result that relay C3 is deenergized andreleases at the end of its slow release period. Five code impulses plusa pause of the 180--80 code span a period of something like two andone-sixth seconds, and hence relay C3, which is provided with a releaseperiod of the order of five seconds, does not release until subsequentto the completion of a second operation or count of the counting relays.That is to say, two counts are required of the counting relays before achange in the position of the control relays is effected, with theresult that an interruption such as may occur at an insulated rail joinlocation does not change the condition of the control relays CI, C2 andC3, and in turn the condition of the cab indicator HS.

Inasmuch as relays 4 and 5 are picked up during each code group, therelays CI and C2 are retained energized. With relay C3 released andrelays Ci and C2 energized, the circuit for the NO lamp is opened atfront contacts H39 and ISI of relay C3. Opening of front contacts Hilland I35 also causes deenergization of the Whistle magnet WM and theWhistle I36 is sounded. The engineman acknowledges this change in thehazard cab indicator by operating the switch SW to pick up the relaySPC. The pick-up circuit for relay SPC includes B terminal, frontcontact 293 of relay LP, front contacts I28 and 529, back contact Hid,contact I i5I46 of switch SW. winding of relay SPC, back contact Ml,front contacts I32, I33 and i2! and to the C terminal. Relay SP0 isretained energized subsequent to switch SW being returned to its normalposition over its own front contact 1:38 in shunt with the contact li5E-4i5. The Whistle magnet WM is now energized over a circuit includingthe following elements: we, i253, I29, I44, MS, 539, Hill, whistlemagnet WM, MI, Hill, Ml, E32, :33 and The lamp 8% of indicator HS is nowprovided with a circuit that includes the elements: 13 terminal, frontcontacts Hi5, I28 and 529, back contact i l i, contact I 55 of switchSW, front contacts iii! and 552 of relays C6 and C2, respec tively, lamp8t, front contacts i53, I56 and 1155, back contact Mi, front contactsI32, I33 and I2l to the C terminal. To sum up, reception of the fat 8-8code current is effective to cause the display of the clear lamp 55 ofindicator TS in a manner previously described, and to display the HAZ86lamp of indicator HS, the change in the signal displayed by theindicator I-IS requiring acknowledgment by the engineman.

Assuming the fixed track hazard to be one of the second degree and thecurrent is of the i8!l code, the operation of the apparatus is simi- 80code. Since relay to be notedand also the whistle magnet contact I I lay5' nor 5 is now operated, both control relays C2 and C3 are deenergi-zedand released at the end of their slow release period. Again. it is thatthe release period of relays C2 and C3 is such as to span at least twocode groups, with the result that at least two counts of the countingrelays are required before a change in the position of the controlrelays is effected. When relays C2 and C3 are released, the NO lamp forindicator HS is extinguished. as before is deenergized. The enginernanwouldacknowledge this change in the indicator HS in the same mannerpreviously pointed out inconnection with the 180- 4 is picked up'duringeach code group, relay Cl is retained energized, arid with relay Cipicked up and relays C2 and C3 deenergizedv a circuit is formed for the50 lamp of indicator HS. This circuit involves the following elements: Bterminal, front contacts I26 and I28, back contact [56, contact I45,front back contact I58, the 5G lamp,

back contact [59, front contact [54, front concator fI-IS to beextinguished.

reflect clear traffic tact [55, back contact I51, front contacts I33 andI26 andC terminal. Hence, the HAZ-5ll"" cab signal is displaye'd'toindicate the approach to a track hazard of the second degree.

If the fixed track hazard is one of the third degree and the code is|80--25, the lamp 56 of indicator LS is displayedv in response to the180 traffic coridifrequency code to reflect clear tions, the same as inprevious cases, and the re-' lay LC, together with the counting relays,are previously described, fact that only three counting relays l, 2 and3 are operated since the code groups contain only three impulses. Underthese circumstances, the three control relays Cl, C2 and C3 are allreleased at the expiration of their slow release period, causing the NOlamp of indiand the whistle magnet to be deenergize'd, sounding whistleI36. The engineman acknowledges the change in the hazard indicator HS byo erating the switch SW to energize relay SPC in the manner previouslypointed out. The picking up of relay SPC prepares a circuit for the 25lamp' of indicator which circuit is completed when the control relaysare released, with the result" that the "HAZ 25 cab signal is displayed.This circuit for the lamp 25 includes the elements: B terminal, frontcontact I26, back contact I60, contact I45, back contact I62, the 25lamp, back contact l63, front contact 155-, back contact lBl,

front contact I21 and the C terminal.

It. is to. be" seen from the foregoing description that, when the"locomotive enters the track'section, the trackway apparatus of which isset to conditions and modified fixed track hazard in the vicinity of thesection, the indicator TS displays a clear traffic signal and. theindicator HS displays the degree of the fixed track hazard, the

in accordance with a response of the apparatus governing indicator IHSbeing such as to require two counts of the group code and. theacknowledging device requiring that the engineman acknowledge the changeinthe hazard indicator.

In he event the trackway apparatus of the section in'the vicinity of thetrack hazard is set to reflect fapproach-restricting trafiic conard',the'operation of the train-carried apparatus would be similar to thatdescribed under clear traffic conditions for the track sections, exceptfor the fact that lamps Fla and Gib of indicator TS are illuminated todisplay the approachrestricting cab signal.

Again, in the event the trackway apparatus for the section inthevicinity of the fixed track ha'zardis set to reflect approach trafficconditions and the code is 15-80, 15-50 or '5-25, depending. upon thedegree of the fixed hazard, the operation of the train-carried apparatusis similar to that described under clear traffic conditions, except forthe fact that lamp 64 of in- .dicator TS is illuminated to display theapproach cab signal and the relay AP is picked up to increase therelease period of relay LC so that relay LC bridges the normal offperiods of the 15 code frequency but is released during the longinterval inserted between the code groups.

In the event this track section in the vicinity of a fixed track hazardis occupied and cautionslow speed traffic conditions exist for a secondor following train, the relays MR and MRI of the second train. are bothinactive. Under these circumstances the control relays A, R and L areall released, causing lamp 6'! of. indicator TS to be illuminated todisplay the caution-slow speed cabsignal. The relays LC and LP, aswellas the counting relays and their associated control relays Ci, C2and C3, are also deenergized and released, the release of relay LPcausing the lamps of the indicator HS to be extinguished and there-,- bypreventing the display of a hazard cab signal under the caution-slowspeed traffic conditions. When relay LLP is released, closing its backcontacts I64 and 165, an auxiliary circuit is provided for the whistlemagnet and the whistle J35 remains silent.

Although I have herein only one form of apparatus embodying myinvention, it is understood that various changes and modifications maybe made therein within the scope of the appended claims withoutdeparting from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. Railway traffic controlling apparatus for a railroad the track ofwhich is characterized by fixed track hazards of different nature andwhich track is divided into insulated track sections for signaling,trackwayapparatus for the section next in the rear of agiven fixed trackhazardincluding traffic governed means and a code transmitter andoperative to supply to the track rails of the section current of any oneof a plurality of different codes according to different trafficconditions in advance of the section, and said code transmitter ofpredetermined construction to modify each of said code currentssupplied-to the rails of the section by a distinctive characteristicselected according to the nature of said fixed hazard.

2. Railway traffic controlling apparatusfor a railroad the track ofwhichis characterized by fixed track hazards of different degrees andwhich track is divided intoinsulatedtrack sections. for signaling,"track-way apparatus for the section next ,in the rear of agiven fixedtrack hazard supply to the track rails of the. section current of anyone of a plu- -rality of. different codes according to different shownand described 7 Cir traffic conditions in advance of the section, andsaid code transmitter provided witha modification predeterminedaccording to the degree of said fixed track hazard to provide for eachof said code currents a distinctive characteristic selected according tothe degree of said fixed track hazard. i

3. Railway trafiic controlling apparatus for a railroad the track ofwhich is characterized by fixed track hazards of different degrees thatrequire different permissible maximum speeds for trains at theirrespective locations and which track is divided into insulated tracksections for signaling, trackway apparatus for the section adjacent agiven fixed track hazard responsive to different trafiic conditions inadvance of the section, and a code transmitter governed by said trackwayapparatus for supplying to the track rails of the section next in therear current impulses at different code frequencies with a distinctivefrequency code for each of said different traific conditions, said codetransmitter provided with a modification predetermined by the degree ofsaid fixed track hazard to separate such current impulses into adistinctive group of impulses which is separated from the preceding andsucceeding groups by a predetermined interval to provide a distinctivegroup code corresponding to the permissible maximum speed for saidhazard.

4. Railway traffic controlling apparatus for a railroad the track ofwhich is characterized by fixed track hazards of different degrees andwhich track is divided into insulated track sections for signaling, atrack circuit for said section next in the rear of a fixed track hazardof a given degree including a source of signaling current, coding meansfor said section operative to code the current of the associated trackcircuit with a different trafiic code for each of a plurality ofdiiferent trafiic conditions in advance of the section, and said codingmeans including a code modifier of a construction predeterminedaccording to the degree of said fixed hazard to provide each of saiddifferent trafiic codes with a distinctive modification selectedaccording to the degree of said fixed hazard.

5. Railway traffic controlling apparatus comprising, a track circuit,trackway coding means operative to supply to said track circuit impulsesof current coded at diiferent frequency codes, according to diiferenttraffic conditions in advance of said track circuit, said coding meansconstructed to arrange the different frequency codes with a group codepredetermined according to a fixed track hazard in advance of said trackcircuit, train-carried receiving means electrically coupled with saidtrack circuit effectively influenced by the impulses of said difierentcodes, a first decoding unit governed by the receiving means selectivelyresponsive to the different frequency codes, a second decoding unitgoverned by said receiving means responsive to said group code, a firstindicator governed by said first unit to display a signal correspondingto the traffic condition reflected by the frequency code, and a secondindicator governed by said second unit to indicate the approach to saidfixed track hazard.

6. Railway trafiic controlling apparatus comprising, a track circuit,trackway coding means operative to supply to said track circuit impulsesof current coded at different frequency codes according to diiferenttrafiic conditions in advance of said track circuit, said coding meansprovided with a predetermined modification to group said frequency codeswith a particular one of a plu rality of different group codes accordingto fixed track hazards of different degrees, train-carried receivingmeans electrically coupled with said track circuit and effectivelyinfluenced by the impulses of said diiferent codes, a first decodingunit governed by the receiving means and selectively responsive to thedifferent frequency codes, a second decoding unit governed by thereceiving means and selectively responsive to said group code, a' firstindicator governed by said first unit, and a second indicator governedby said second unit.

7. Railway trafiic controlling apparatus comprising, a track circuit,trackway coding means operative to periodically supply to said trackcircuit current impulses of like duration coded at different codes, eachof said cod-es consisting of recurring groups of impulses with eachgroup made up of a distinctive number of impulses and each groupseparated from the preceding and succeeding groups by a predeterminedinterval, train-carried receiving means electrically coupled with saidtrack circuit and effectively influenced by said current impulses,decoding means governed by the receiving means operative to count theimpulses of each group to distingush between the difierent codes, andcontrol means selectively governed by the decoding means according tothe number of impulses of a code group and characterized by aretardation in its operation to require counting of -the impulses of twogroups to eifect the corresponding operation.

8. Railway trafiic controlling apparatus comprising, a track circuit,trackway coding means operative to supply to said track circuit currentimpulses of different frequency codes according to different trafficconditions in advance of said track circuit, said coding meansconstructed to arrange the impulses supplied to the track circuit in adistinctive group code predetermined according to the degree of a givenfixed track hazard, said group code made up of recurring groups ofimpulses with each group consisting of a number of impulses distinctivefor the code and separated from the preceding and succeeding groups byan interval greater than the interval between successive impulses of thecode, train-carried receiving means eifectively influenced by said trackcircuit, a first and a second decoding means governed by the receivingmeans, said first decoding means selectively responsive to the differentfrequency codes and characterized to bridge the interval betweensuccessive groups, said second decoding means made active by saidinterval between successive groups and selectively responsive to saidgroup code, and a first and a second cab indicator governed by the firstand second decoding means respectively.

9. In combination with a stretch of railway track having at difierentpoints fixed track hazards that require due to their diiferent degreesdifferent permissible maximum speeds for trains at their respectivelocations which speeds are less than that required at other locationsand which track is formed into insulated track sections for signaling, atrack circuit for a section in the rear of a given fixed track hazard,trackway coding means for said section operative to supply to the trackcircuit of the section current impulses of different code frequenciesaccording to different traffic conditions in advance of the section, andto group the impulse of the dilferent frequency codes supplied to thetrack circuit of the section into successive groups each of whichconsists of ill) traffic condition of the section, a second decodingunit governed by the receiving means selectively responsive to saidgroup code to display a cab sig-' to the permissible maximum hazard inadvance of the secnal corresponding speed at the fixed tion.

10'. In combination, a code following relay capable of operating itsarmature in step with current impulses periodically supplied to itswinding when such impulses are coded atany one of a plurality ofdifferent frequency codes and when any one of said frequencycodes ismodified by the impulses being arranged according to any one of aplurality of different group codes with each group of a code separatedfrom the preceding and succeeding groups by an interval greater than theinterval between two successive impulses of the same code, a firstdecoding means governed by said armature'selectively responsive to thedifferent frequency codes and characterized to bridge the intervalsbetween the successive groups, retardation means governed by saidarmature including a relay which is retained energized during theinterval between successive impulses of the codes and is released duringthe interval between the different groups, and a second decoding meansgoverned by said armature and said relay selectively responsive to thedifferent group codes.

11. In combination, a code following relay capable of operating itsarmature in step with current impulses periodically supplied to itswinding when such impulses plurality of different frequency codes andwhen any one of said frequency codes is modified by the impulses beingarranged according to any one of a plurality of different group codeswith each group of a code separated from the preceding and succeedinggroups by an interval greater than the interval between two successiveimpulses of the same code, a first decoding means governed by saidarmature selectively responsive to the different frequency codes andcharacterized to bridge the intervals between the successive groups,retardation means governed by said armature including a relay which isretained energized during the interval between successive impulses ofthe codes and is released during the interval between the differentgroups, and a second de-' coding means governed by said armature andsaid relay and including a chain of counting relays which aresequentially operated by the successive impulses of a code group todifferentiate between the different group codes by the number of relaysoperated. r

12. In combination, a code following relay capable of operating itsarmature in step with current impulses periodically supplied to itswinding when such impulses are coded at any one of a plu-,-,

rality of different frequency codes and when any one of said frequencycodes is modified by the impulses being arranged according to anyone ofa plurality of different'group codes with each group i of a codeseparated from the preceding and succeeding groups by an intervalgreater than the interval between two successive impulses of the samecode, a slow release relay governed by said armature, means controlledby said armature in are coded at any one of a response to the frequencycodes to automatically adjust the slow release period of said slowrelease relay to cause the relay to bridge" the interval'betweensuccessive impulses of the code operating the armature and to bereleased during the interval between successive groups of the code, achain of counting relays sequentially energized in response to operationof said armature, and circuit means controlled bysaid slow release relaywhen released to deenergize the counting relays" to start a newoperation of the counting relay with each group of a code. I

13. In combination, a code following relay capable of operating itsarmature in step with current impulses periodically supplied to itswinding when such impulses are coded at any one of a pluralityofdifferent frequency codes and when any one of said frequency codes ismodified by the impulses being arranged according to any one of samecode, a slow release relay governed by said armature, means controlledby said armature in response to the frequency codes to automaticallyadjust the slow release period of said slow release relay to cause therelay to bridge theinterval between successive impulses of the codeoperating the armature and to be released during the interval betweensuccessive groups of the code, a chain of counting relays sequentiallyenergized in response to operation of said armature, circuit meanscontrolled by said slow release relay when released to deenergize thecounting relays to start a new operation of the counting relay with eachgroup of a code, signaling means governed by said counting relays todisplay a particular signal for each of said group codes, and anotherslow release relay periodically energized by each operation of saidarmature effective when released to prevent,

the signaling means from displaying any signal.

1.4. In combination, a code following relay capable of operating itsarmature in step with current impulses periodically supplied to itswinding when such impulses are coded at any one of a plurality ofdifferent frequency codes and when the impulses of any one ofsaidfrequency codes are arranged according to any one of a plurality ofdifferent group codes with each group of impulses separated from thepreceding and succeeding groups by an interval greater than the intervalbetween two successive impulses of the same code, a first decoding meansgoverned by said armature selectively responsive to the differentfrequency codes, retardation means governed by said armature including aslow release relay which is retained energized during the intervalbetween successive impulses of the codes and is released during theinterval between the different groups,

a second decoding means governed by said armature including a chain ofcounting relays which are sequentially energized in response tooperation of said armature, circuit means controlled by said at othertimes supply said code following relay a frequency code arranged with agroup code.

15. In combination with a stretch of railway track characterized byfixed track hazards of different degrees and which track is divided intoinsulated track sections for signaling, a train to travel on said track,train-carried receiving means effectively infiuenced'by the trackcircuit of the section occupied by the train, a first decoding unitgoverned by said receiving means selectively responsive to current ofdifferent frequency codes to display different indications of a firstcab signal, a second decoding unit governed by the receiving meansselectively responsive to different group codes to display differentindications of a second cab signal, a track circuit for a selectedsection, trackway apparatus including a code transmitter responsive todifferent traffic conditions in advance of that section to supply tosaid track circuit current impulses of different code frequencies todisplay an indication of said first cab signal according to trafficconditions, and said code transmitter predetermined in constructionaccording to the degree of a given fixed hazard in advance of saidsection to arrange the current impulses of said track circuit in aselected group code to display a predetermined indication of said secondcab signal.

16. Railway trafiic controlling apparatus for a railroad the track ofwhich is characterized by fixed track hazards of at least two differentdegrees and which track is divided into successive insulated tracksections for signaling, a track circuitfor each section; three codetransmitters of different constructiton and all of which are effectiveto produce at least two different frequency codes to correspond todifferent traific conditions, one of which transmitters is effective toarrange such frequency codes with a first group code to correspond to afirst degree fixed track hazard and a second one of which transmittersis effective to arrange such frequency codes with a second group code tocorrespond to a second degree fixed track hazard; trackway apparatus fora selected section selectively responsive to at least two differenttraflic conditions in advance of that section, said trackway apparatusoperative to govern any predetermined one of said code transmitters forcorrsepondingly coding the current supplied to the track circuit for thesection next in the rear of said selected section, and train-carriedmeans effectively influenced by said track circuit when occupied by thetrain and selectively responsive to such frequency and group codes.

FRANK H. NICHOLSON.

